Improvements in or relating to explosive charges

ABSTRACT

A liner for a shaped charge, the liner being a generally conical liner, in which the liner is formed from metal or metal alloy and in which the liner has an internal apex angle in the range of approximately 105-110 degrees.

The present invention relates generally to explosive charges and particularly, but not exclusively, to shaped charges.

A typical shaped charge has a concave metal hemisphere or cone (known as a liner) backed by a high explosive, all in a casing. When the high explosive is detonated a detonation wave is generated; this causes the metal liner to be compressed and squeezed forward, forming a high velocity metallic jet.

The present invention seeks to provide improvements in or relating to shaped charges.

An aspect of the present invention provides a liner for a shaped charge, the liner being a generally conical liner, in which the liner is formed from metal or metal alloy and in which the liner has an internal apex angle in the range of approximately 105-110 degrees.

The angle may be in the range of approximately 107-109 degrees.

The angle may be approximately 108 degrees.

A further aspect provides a liner for a shaped charge, the liner being, in which the liner is formed from metal or metal alloy and in which the liner is formed as a section of a hemisphere.

In aspects and embodiments of the present invention the liner may be formed from a low-density metal or alloy that is capable of burning.

In some embodiments the liner is formed from magnesium, copper or aluminium or alloys thereof.

Examples of embodiments include: a copper jet forming cone; a copper explosively formed projectile; and a magnesium jet forming cone.

Additional thickness could, for example, be used to maintain roughly the same mass for a lower density metal.

A further aspect provides an explosive ordnance neutralisation system comprising a low-order explosive shaped charge having a liner, the liner being a die-cast, jet-forming cone having a cone angle of approximately 108 degrees.

A further aspect provides an explosive ordnance neutralisation system comprising a low-order explosive shaped charge having an EFP-forming liner, the liner having a cone angle of approximately 108 degrees.

Systems formed in accordance with the present invention may operate in such a way to produce a non-explosive reaction that does not cause a detonation, known as a low order event.

The liner is systems formed in accordance with the present invention may be formed from magnesium or a magnesium alloy.

According to a further aspect of the present invention there is provided a liner for a shaped charge, the liner being a generally conical metal liner, in which the liner is formed from magnesium and in which the liner has an internal apex angle in the range of approximately 105-110 degrees.

The angle may be in the range of approximately 105-110 degrees, for example 107-109 degrees; such as approximately 108 degrees.

In some aspects and embodiments the metal liner is formed by die casting. This helps to avoid porosity (which can prevent jet formation). In other embodiments the metal liner may be formed by hot-stamping from metal sheet.

In some embodiments the material of the liner has a generally uniform thickness.

The present invention also provides a shaped charge fittable with, fitted with, or having a liner as described herein.

The present invention also provides an explosive ordnance neutralisation system comprising an explosive shaped charge designed to produce a low-order event in a target munition having a liner, the liner being a die-cast magnesium jet-forming cone having a cone angle of 108 degrees.

Explosives can be categorised by their speed of detonation: low explosives which burn violently or high explosives which detonate. The speed of deflagration or detonation are a measure of the power and destructive force of an explosive.

High explosives detonate, producing a shockwave traveling through the explosive material at supersonic speed (typically from 1,800 to 8,000 m/s). When attempting to neutralise a munition in the process of explosive ordnance disposal detonating the munition is not ideal because the damage caused to the surroundings can be significant. It is possible to cause munitions to deflagrate or burn rather than detonate in a process commonly referred to as a “low-order” event. Unlike low explosives such as black powder which can only deflagrate, specific conditions must be maintained in order to cause a high explosive to violently enough to rapidly destroy a munition and consume a significant proportion of the explosive without it undergoing a transition to detonation. Such a low-order event may be preferable in some situations.

Shaped charges may be used to cause explosive in a munition to react, and the type of reaction depends largely on the size, shape and material of the charge. If too much energy is imparted into the munition, it may shock to detonation. Conversely, imparting too little energy may cause the reaction of not sustain itself and self-extinguish. Ideally, the target explosive shall ignite and with suitable confinement from the munition's outer casing, the pressure within the case shall increase, accelerating the speed of deflagration, causing further pressure increases until the munition's case is unable to retain the high internal pressure and bursts. The munition is opened up, the explosive either burned or scattered and the entire device rendered safe.

This invention relates to a shaped charge projectile design that produces the ideal conditions for producing a low-order event by using a low-density metallic material capable of burning. The shape of the projectile is such that it is in the transition phase between a traditional conical shaped charge capable of deep penetration and an explosively formed projectile (EFP) capable of traveling great distances. As such it lacks the deep penetrative power of a more conventional shaped charge, typically made from copper having a cone angle between 70 and 45 degrees but has greater penetration than a comparably sized EFP which would form a larger diameter entry hole.

Different aspects of the present invention may be used separately or together.

Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with the features of the independent claims as appropriate, and in combination other than those explicitly set out in the claims.

Referring now to the drawings, wherein like reference numbers are used to designate like elements throughout the various views, several embodiments of the present invention are further described by way of example, in which:

FIGS. 1-3 illustrate a charge;

FIGS. 4-6 illustrate a further example of a charge of the type described in relation to FIGS. 1 to 3; and

FIGS. 7-11 illustrate sections showing distinct sizing and projectiles.

The example embodiments are described in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein.

Accordingly, while embodiment can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included. Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate.

Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealised or overly formal sense unless expressly so defined herein.

In the following description, all orientational terms, such as upper, lower, radially and axially, are used in relation to the drawings and should not be interpreted as limiting on the invention.

Referring first to FIGS. 1 to 3 there is shown a charge generally indicated 10.

The charge 10 comprises a generally cylindrical bottle-like container 15. The container includes a generally cylindrical body 16. At one end of the body an inclined wall 17 extends radially inwards. At the centre of the wall 17 a neck 18 is provided and has a central passage 19. In this embodiment a separate screw threaded collar 20 is provided for receiving a detonator and can be screwed onto the neck 18.

The other end of the body 16 is closed by a partition/barrier/barrier membrane 25. The membrane 25 has an annular flange 26 that fits onto the open end of the body. A short annular skirt 27 depends from the flange. The skirt 27 is positioned to fit into the interior of the body.

At the centre of the flange 26 a longitudinal annular leg 29 extends and is closed by a concave plate 30 (so the plate 30 is “inside” the body).

The interior of the body provides an enclosure 32 for receiving liquid explosive, such as nitromethane.

A projectile in the form of a die-cast magnesium metal cone 37 having a cone angle of 108 degrees is provided. The shape/profile of the cone 37 is complimentary with the shape of the plate/leg. The charge diameter is greater than the projectile diameter.

In some ways, therefore, this could be thought of as a bottle with the correct front/bottom profile to receive a liner.

The container could be formed from a plastics material.

This embodiment includes a plastic surface between the explosive and the liner which facilitates containing a liquid without leaking, while not adversely affecting the performance of the cone.

This embodiment uses liquid explosives. Other embodiments use a more conventional shaped charge (factory or user-filled) which uses plastic explosive or a cast explosive.

A further example of a charge of the type described in relation to FIGS. 1 to 3 is shown in FIGS. 4 to 6.

The charge 110 is shown assembled in FIG. 6. The body 116 can be filled with liquid explosive and the collar 120 is screwed onto the body 116. A detonator 140 is fitted into the collar and a projectile 137 is fitted into the membrane 125.

In use, activation of the detonator 140 causes detonation of the liquid explosive material, which in turn causes projection of the projectile 137.

This embodiment provides the feature that there is a plastic surface between the explosive and the liner which facilitates containing a liquid without leaking while not adversely affecting the performance of the cone.

These embodiments use liquid explosives. In other embodiments a shaped charge (factory or user-filled) which uses plastic explosive or a cast explosive may be provided.

The explosive used in aspects and embodiments of the present invention could, for example, be a factory cast or pressed explosive, a user-filled plastic explosive or a liquid binary explosive. They key is the detonation velocity.

FIGS. 7 to 11 are sections showing two sizes and three projectiles for comparison: Copper jet forming cone, Copper explosively formed projectile and Magnesium 108 degree Magnesium jet forming cone. Additional thickness can be used to maintain roughly the same mass for a lower density metal.

Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention. 

1. A liner for a low-order explosive shaped charge, the liner being a die-cast cone, the die-cast cone being formed from magnesium or a magnesium alloy, the die-cast cone having an internal apex angle in the range of approximately 108 degrees. 2-12. (canceled)
 13. A liner as claimed in claim 1, in which the material of the cone has a generally uniform thickness.
 14. A shaped charge having a liner as claimed in claim
 1. 15. A shaped charge comprising a generally cylindrical bottle-like container comprising a generally cylindrical body, at one end of the body an inclined wall extends radially inwards, at the centre of the wall a neck is provided and has a central passage for receiving a detonator, the other end of the body is closed by a plate, a projectile in the form of a liner is provided, the shape of the liner is complimentary with the shape of the plate.
 16. A charge as claimed in claim 15, in which the container is formed from a plastics material.
 17. A charge as claimed in claim 15, in which the liner is a cone.
 18. A system as claimed in claim 16, in which the cone angle is in the range 107-109 degrees.
 19. A system as claimed in claim 17, in which the cone angle is approximately 108 degrees.
 20. A system as claimed in claim 15, in which the liner is formed from magnesium or a magnesium alloy.
 21. A charge as claimed claim 15, in which in the diameter of the body is greater than the diameter of the liner.
 22. A charge as claimed in claim 15, in which the body is filled with liquid explosive, plastic explosive, a cast explosive, a factory cast or pressed explosive, a user-filled plastic explosive or a liquid binary explosive.
 23. A charge as claimed in claim 15, in which the body is factory-filled with explosive material.
 24. A charge as claimed in claim 15, in which the body is user-filled with explosive material.
 25. A charge as claimed in claim 15, in which the projectile is a copper jet forming cone.
 26. A charge as claimed in claim 15, in which the projectile is a copper explosively formed projectile.
 27. A charge as claimed in claim 15, in which the projectile is a magnesium jet forming cone.
 28. An explosive ordnance neutralisation system comprising a low-order explosive shaped charge, in which the charge comprises a generally cylindrical bottle-like container, the container includes a generally cylindrical body, at one end of the body an inclined wall extends radially inwards, at the centre of the wall a neck is provided and has a central passage, a separate screw threaded collar is provided for receiving a detonator and can be screwed onto the neck, the other end of the body is closed by a membrane, the membrane has an annular flange that fits onto the open end of the body, a short annular skirt depends from the flange, the skirt is positioned to fit into the interior of the body, at the centre of the flange a longitudinal annular leg extends and is closed by a concave plate so the plate is inside the body, the interior of the body provides an enclosure for receiving liquid explosive, a projectile in the form of a die-cast magnesium metal cone having a cone angle of 108 degrees is provided, the shape of the cone is complimentary with the shape of the plate/leg, the charge diameter is greater than the projectile diameter. 